<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>网页布局</title>
    <style>
        header{
            height: 50px;
            background-color: blueviolet;
        }
        main{
            border: 1px solid red;
            background-color: rgb(209, 250, 182);
            /* height: 600px; */
        }
        footer{
            height: 200px;
            background-color: rgb(247, 152, 152);
        }
        section{
            width: 400px;
            height: 500px;
            background-color: rgb(148, 196, 136);
            border:1px solid black;
            float: left; 
        }
        .clear{
            clear: both;
        }
        .clearfix::after{
            content: '';
            display: block;
            clear: both;
            /* zoom: 1;
            height: 0; */
        }
        /* main::after{
            content: '';
            display: block;
            clear: both;
        }
        .content::after{
            content: '';
            display: block;
            clear: both;
        } */
    </style>
</head>
<body>
    <header></header>
    <main class="clearfix">
        <section></section>
        <section></section>
        <!-- <div class="clear"></div> -->
    </main>
    <div class="content clearfix">

    </div>
    <footer></footer>
</body>
</html>